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  <title>转换指定字符</title>
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  <div id="layout-content"><div id="function.strtr" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">strtr</h1>
  <p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">strtr</span> &mdash; <span class="dc-title">转换指定字符</span></p>

 </div>
 
 <div class="refsect1 description" id="refsect1-function.strtr-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="methodname"><strong>strtr</strong></span>
    ( <span class="methodparam"><span class="type">string</span> <code class="parameter">$str</code></span>
   , <span class="methodparam"><span class="type">string</span> <code class="parameter">$from</code></span>
   , <span class="methodparam"><span class="type">string</span> <code class="parameter">$to</code></span>
   ) : <span class="type">string</span></div>

  <div class="methodsynopsis dc-description">
   <span class="methodname"><strong>strtr</strong></span>
    ( <span class="methodparam"><span class="type">string</span> <code class="parameter">$str</code></span>
   , <span class="methodparam"><span class="type">array</span> <code class="parameter">$replace_pairs</code></span>
   ) : <span class="type">string</span></div>

  <p class="para rdfs-comment">
   该函数返回 <code class="parameter">str</code> 的一个副本，并将在 <code class="parameter">from</code> 中指定的字符转换为 <code class="parameter">to</code> 中相应的字符。
   比如， <em>$from[$n]</em>中每次的出现都会被替换为
   <em>$to[$n]</em>，其中 <em>$n</em> 是两个参数都有效的位移(offset)。
  </p>
  <p class="para">
   如果 <code class="parameter">from</code> 与 <code class="parameter">to</code> 长度不相等，那么多余的字符部分将被忽略。 <code class="parameter">str</code> 的长度将会和返回的值一样。
  </p>
  <p class="para">
   If given two arguments, the second should be an <span class="type"><a href="language.types.array.html" class="type array">array</a></span> in the
   form <em>array(&#039;from&#039; =&gt; &#039;to&#039;, ...)</em>. The return value is
   a <span class="type"><a href="language.types.string.html" class="type string">string</a></span> where all the occurrences of the array keys have been
   replaced by the corresponding values. The longest keys will be tried first.
   Once a substring has been replaced, its new value will not be searched
   again.
  </p>
  <p class="para">
   In this case, the keys and the values may have any length, provided that
   there is no empty key; additionally, the length of the return value may
   differ from that of <code class="parameter">str</code>.
   However, this function will be the most efficient when all the keys have the
   same size.
  </p>
 </div>


 <div class="refsect1 parameters" id="refsect1-function.strtr-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>

    
     <dt>
<code class="parameter">str</code></dt>

     <dd>

      <p class="para">
       待转换的<span class="type"><span class="type 字符串">字符串</span></span>。
      </p>
     </dd>

    
    
     <dt>
<code class="parameter">from</code></dt>

     <dd>

      <p class="para">
       <span class="type"><span class="type 字符串">字符串</span></span>中与将要被转换的目的字符 <code class="parameter">to</code> 相对应的源字符。
      </p>
     </dd>

    
    
     <dt>
<code class="parameter">to</code></dt>

     <dd>

      <p class="para">
       <span class="type"><span class="type 字符串">字符串</span></span>中与将要被转换的字符 <code class="parameter">from</code> 相对应的目的字符。
      </p>
     </dd>

    
    
     <dt>
<code class="parameter">replace_pairs</code></dt>

     <dd>

      <p class="para">
       参数 <code class="parameter">replace_pairs</code> 可以用来取代 <code class="parameter">to</code> 和 <code class="parameter">from</code> 参数，因为它是以  <em>array(&#039;from&#039; =&gt; &#039;to&#039;, ...)</em> 格式出现的数组。
      </p>
     </dd>

    
   </dl>

  </p>
 </div>

 
 <div class="refsect1 returnvalues" id="refsect1-function.strtr-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   返回转换后的<span class="type"><span class="type 字符串">字符串</span></span>。
  </p>
  <p class="para">
   如果 <code class="parameter">replace_pairs</code> 中包含一个空<span class="type"><span class="type 字符串">字符串</span></span>（<em>&quot;&quot;</em>）键，那么将返回 <strong><code>FALSE</code></strong>。
   If the <code class="parameter">str</code> is not a scalar
   then it is not typecasted into a string, instead a warning is raised and 
   <strong><code>NULL</code></strong> is returned. 
  </p>
 </div>


 <div class="refsect1 examples" id="refsect1-function.strtr-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-5988">
    <p><strong>Example #1 <span class="function"><strong>strtr()</strong></span> 范例</strong></p>
    <div class="example-contents">
<div class="phpcode"><pre><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br />$addr&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">strtr</span><span style="color: #007700">(</span><span style="color: #0000BB">$addr</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"äåö"</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"aao"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</pre></div>
    </div>

   </div>
  </p>
  <p class="para">
   The next example shows the behavior of <span class="function"><strong>strtr()</strong></span> when
   called with only two arguments. Note the preference of the replacements
   (<em>&quot;h&quot;</em> is not picked because there are longer matches)
   and how replaced text was not searched again.
  </p>
  <div class="example" id="example-5989">
   <p><strong>Example #2 使用两个参数的 <span class="function"><strong>strtr()</strong></span> 范例</strong></p>
    <div class="example-contents">
<div class="phpcode"><pre><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br />$trans&nbsp;</span><span style="color: #007700">=&nbsp;array(</span><span style="color: #DD0000">"hello"&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">"hi"</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"hi"&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">"hello"</span><span style="color: #007700">);<br />echo&nbsp;</span><span style="color: #0000BB">strtr</span><span style="color: #007700">(</span><span style="color: #DD0000">"hi&nbsp;all,&nbsp;I&nbsp;said&nbsp;hello"</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$trans</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</pre></div>
    </div>

    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
hello all, I said hi
</pre></div>
    </div>
  </div>
  <p class="para">
   The two modes of behavior are substantially different. With three arguments,
   <span class="function"><strong>strtr()</strong></span> will replace bytes; with two, it may replace
   longer substrings.
  </p>
  <div class="example" id="example-5990">
   <p><strong>Example #3 <span class="function"><strong>strtr()</strong></span> behavior comparison</strong></p>
    <div class="example-contents">
<div class="phpcode"><pre><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /></span><span style="color: #007700">echo&nbsp;</span><span style="color: #0000BB">strtr</span><span style="color: #007700">(</span><span style="color: #DD0000">"baab"</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"ab"</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"01"</span><span style="color: #007700">),</span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">$trans&nbsp;</span><span style="color: #007700">=&nbsp;array(</span><span style="color: #DD0000">"ab"&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">"01"</span><span style="color: #007700">);<br />echo&nbsp;</span><span style="color: #0000BB">strtr</span><span style="color: #007700">(</span><span style="color: #DD0000">"baab"</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$trans</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</pre></div>
    </div>

    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
1001
ba01
</pre></div>
    </div>
  </div>
 </div>


 <div class="refsect1 seealso" id="refsect1-function.strtr-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="str_replace.html" class="function" rel="rdfs-seeAlso">str_replace()</a> - 子字符串替换</span></li>
    <li class="member"><span class="function"><a href="preg_replace.html" class="function" rel="rdfs-seeAlso">preg_replace()</a> - 执行一个正则表达式的搜索和替换</span></li>
   </ul>
  </p>
 </div>

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